Peters



N. PETERS. FHOTOALSTHOGRPHEP, WASHINGTON. D

UNITED STATES PATEN T OFFICE,

JNO. DOMINIS, OF THE SANDIVICH ISLANDS.

INSTRUMENT FOR MEASURING SAILS.

Specification of Letters Patent N o.

To all whom t may concern:

Be it known that I, JOHN` DoMINis, a citizen of the United States 0f America, but now residing in the Sandwich Islands, in the Pacific Ocean, have invented new and useful mathematical scales and tables for determining the gores, roaches, and proportions of sails for cutting the same from rolls of canvas.

The said invention, the principles thereof, and manner in which I havecontem-v plated the application of the same by which it may be distinguished from others of a like character, together with such parts or combinations I claim as new and desire Letters Patent therefor granting to me an exclusive property in the same for fourteen years, I have herein set forth and described, which description taken in connection with the accompanying drawings herein referred to forms my specification.

As sails of diierent kinds and for different vessels are formed of strips of cloth or canvas sewed together, after they are cut to proper shapes and lengths, and as it is customary to cut said strips from what is usually termed a roll or bolt of canvas, it becomes desirable to accomplish the same, with as little waste of material as possible, or in other words so to measure the lengths and gore of each strip that when the whole are sewed together, the sail thus formed shall possess the required shape, and in nautical language set well when adjusted and exposed to the action of the wind.

In order that the use and adaptation of my improvements may be more particularly understood, I shall proceed to illustrate the mode usually practiced of cutting the cloths of a sail from a long or extended strip of canvas.

IVe will suppose for the sake of explanation that we wish to cut up a roll of canvas for the purpose of converting the same into a sail usually termed a jib. To cut the first cloth (presuming the canvas is square on the end) it is necessary to set up from the end a certain determined distance (called the gore on the foot, and which we will able mark.

suppose six and one half inches), on either 2,790, dated September 30, 1842,

selvage of the canvas and there make a suit- Then cut from the said mark diagonally across the canvas to the extreme point of the opposite selvage and thus we shall have formed the foot gore for the iirst cloth. Next measure upv on the selvage from. the foot or mark above mentioned the length of the after leach (which suppose forty two feet), then from the extremity of the distance so measured set downward another certain determined distance called the gore on the stay and which we will suppose to equal four feet and four inches. Next following the filling thread so marked across the strip of canvas to the opposite selvage and make a suitable mark thereon, which mark will be in a line perpendicular to the selvage. Next cut the cloth from the last mentioned mark diagonally to the mark, denoting the length of the first cloth and thus we form the stay gore for the first and second cloths. Turn the canvas so as to bring the longer selvage even in a line with the shorter selvage of the first cloth. Measure down by thiscloth fo-r the length of the second cloth and mark it; thence take a thread as before to the opposite selvage; thence set off six and one-half inches (the foot gores) downward; mark it and cut diagonally as before to the mark ldenoting the length of the seco-nd cloth on the opposite selvage, and thus we obtain the foot gore or slope of the second and third cloths. Turn the canvas on the foot, as before, on the head, and continue measuring turning and cutting until all the cloths are so prepared.

The above is the process by which a bolt of sail cloth is generally cut up, and from the same it will be easily seen that in o-rder to prevent waste and to make the cloth come together so as to give to the sail its intended form when finished, great care is requisite in finding the true distances to measure down on the selvage to obtain the gores on the stay and foot. v

Having thus premised, I shall now proceed to explain the construction and application of the mathematical scales and tables.

Figure l, represents the different scales attached to their board. Two scales A and B being placed parallel to each other and at a suitable distance apart are screwed down or otherwise properly secured to a table or board a Z) c d, Fig. l. The inner edge of the scale A is divided into inches, which divisions are subdivided into tenths, or in any other convenient manner. A semi circle e f g, graduated to degrees' is described on the scale A as seen in the drawg ing the Ychord of the semi circle Vbeing formed by the inner edge of the rulers. The opposite scale B has its inner edge divided and subdivided in a similar manner to the first; and each of these scales has an elongated slot 71, z' y' 7c formed in it parallel with its inner edge. Fach of the slots is placed directly over a suitable groove or channel cut out of the wood under the same, and which is of sufficient breadth and depth to receive and allow full play back and forth the heads of common screws Z m a 0, in which screws the milled clamping nuts p, g, r, s, are screwed, the said nuts serving to confine the rulers E, F, &c. in different positions in which they may be adjusted to each other on the board as will be hereafter explained. rlhe heads of the screws Z, m, fn, 0 being larger in diameter than the width Ofthe slots it, z', y', 7c, are drawn'upwards against the underside of the scales A, B, or sides of the slots, when the milled clamping nuts are screwed down, and thus the rulers or scales E, F, are confined when adjusted to any particular position. A section of one of the screws, milled nuts, scales, and channel or groove under the latter is given in Fig. 7 where c is the screw, a the milled nut, Z Z the scale, o the channel in the woodwork, fo-r the head c of the screw b to move in.

The center o-f the semicircle c f g has a screw S projecting perpendicular-ly therefrom, on which a clamping nut or head U is secured and serves to confine the rulers C and D, &c., in any desirable positions. The graduations or divisions of the ruler r commence at the center of the semicircle e f g, and are numbered or extend each way as represented by the Figs. 3, 4, &c., in the ligure. The divisions of the ruler B are similar and are directly opposite those of the ruler A as exhibited in the drawingthat is to say, the straight or base line, from the center of the screw t or semicircle e f g, to the zero of the opposite ruler, is perpendicular to the inner edges of each ruler.

rlhe rulers C, D are formed as represented in the drawing, in which it will be observed that their ends resting on or near the graduated semicircle e f g, are pointed and their edges chamfered for the convenience of reading the angular distances of each ruler on the semicircle, which will be hereafter more particularly explained. The rulers C and D are divided into inches and subdivided into tenths commencing from the center of the semicircle e f g, and denoted by Figs. 2, 8, Ll, 5, &c., as represented in the drawing.

rlwo other scales or rulers E F are joined together, at one end of each, by a common rule joint, so as to be easily opened and closed or adjusted to any required angle with each other. Each ruler-has an elongated slot fu LU-c w cut through the same, through which the clamp screws pass, which confine the rulers in any required position on the board. At the point of junction of the rulers E F, and situated under the same, a full graduated circle m is so aliixed as to be freely revolved or turned about on its axis, the said axis passing through the c-enter of the oint of the rulers, and having a small wire point or pin y projecting upward perpendicularly therefrom, see Figs. 9 and l0. Small holes e e a are drilled through the divisions of the rulers C and D and the pin 1/ is passed through either of these holes according to circumstances which will bc more particularly understood or explained hereafter.

The circle as is graduated to degrees and has a ruler G connected to it, as seen in the figure, and whose ends project beyond the circle as therein denoted. The diameter of the circle being extended beyond the circumference is marked on the projecting ends by a line passing through thecenter of the upper face of the entire ruler, as will be seen by reference to the drawing.

Another ruler H formed and divided into inches and lengths and having clamp screws and nuts as represented in the drawing, will be hereafter explained as also a curved ruler I one end of which is placed on the center pin or screw f and is formed with holes and o-therwise shaped as represented partly by dotted lines and partly as otherwise exhibited in the drawing. The other end of the ruler I has an elongated slot Z2 c, through which a sliding screw passes upward from the slot in the ruler B, and by the milled nuts thereon we are enabled to confine the ruler in whatever position we place the same on the hoard a L c' CZ as .will be readily understood by inspection of the drawing. The ruler I is for obtaining the roach and sweep of sails as will be hereinafter explained.

A card or sheet of paper e f gf 7L is laid on the board a c Z between the rulers A and B. @ne edge of the paper viz, e g is to be cut perfectly straight and is to be placed in continuity with the inner or gradnated edge of the ruler A, and to this edge f lines are drawn parallel to.' the same and to each other at am distance therefrom and* apa-rt from each other, proportionate to the widths of cloth or canvas used in making the sail. For canvas `of .diierent widths there should he sepa-rate `sheets of paper, proper ruled for each, which may be used as occasion requires.

If .our canvas is twenty nine inches wide and .the seams take up `one inch thereof we rule the lines ata distance apart from each other' proportionate to twenty eight inches, which if .we :use a `scale vof tire feet to an inch, would `equal seven tifteenths of an inch. Also for cloths of twenty three inches width, .dedncting one inch for the seams, we

have twenty two inches, which if we use the t above scale of ive feet to an inch, will give 11s eleven thirteenths of an inch, for the dis.-`

r tance for ruling the lines apart from. each Cloths of 22 makes.

No.1 No. 2l No. 3 No. 4; No. 5 No.6 No '7 No.8 No.1). No.1() No.1-1' No.1 2l No 13 N011 No 15 No.1 No.17 No 1S No.1()` No. 2 0

Inl In. In. 111; In; :If/L. [77; I/n. Tfn. In.: jLn. L77, In. :Inl In. `171. In 1:011111212121-3 1314141515151751617171.718 2 `1 2 :2 2 :2 `2:3 2 4 :2 l5 2 .5 y2V 7 2 87:2 8 2 v9 2:10 211 212 -212 213 14 2 15 2.16 3 1.8.2 3 :3 3 `5 3 `6 :3 7 ,3 8 319 .3:12313 314 315 `316317318 320321322324 4 2 4 3 4 5 4 -6 4 7 4 9 41:1 414 415 417 418 420 421 423 4:24 426 428 4:29 431 .5 2 `5 4 .5 6 .5 `s 510 5 `12 5 14 `5 .17 :5 :1.9 .5 .2.1 .5 22 5 25 :.5 .27 5 29 :5.31 .5:33 .5.3.5 5:37 5:38 6 2 -6 5:67:6-91612614 616 621 3,23 6 26 628 :6399921634669 6,399.42 644 64.6 7 `3 7 v5 7 :8 `711713716 719 `'124 727 7:30 732 73,5 :,738 V740 7,43 746 749 7 51 754 8 :3 8 16 8 :.9 :812 :8.15 8:19 :8:22 `828 831834 887 `840 843 846 849 `8 52 @5 6 8 59 862 9 4 9 79109141111719219241 :9319359.38 942 9.45 `9.49 :9 52 :9 55 95.9- 62 9:66 970 :10 4 `10 `8 10 l2 .10 16 10 19 `10 23 :1 0 l27 :10 :35 10 3.9 .10 43 -10 .47 .1 0 50 10 A,54 10 58 10 61 10 66 1 70 10 `7 4 10 78 11 4 .11 9 11 13 11 17 1:1 21 11 26 11,30` :11 38 1:1 43 `11 47 `11 11 56 i11 :60 11.64 11-68 `11 73 11 77 11 81 11 86 `12 .5 12 :9 12 :14 :12 19 12 23 .12 28 12 :331: :12 42 12 47 `12 V51 12 y56 12 61 12 :6 6 .12 70 12 74 12 80 12 84 12 89 .12 `9 4 113 5 13 `10 13 15 13 20 13 25 :13 .30 13 35 :13 :46 13 51 13 56 .13 61 13 66 13 V71 13 76 13 .80 13 86 `13 `92 .13 .96 .13102 :14 :6 14 11 V1:4 16 14 -22 41.4.27 .14 `33 1:4 38 14 r.49 14 55 14 .60 14 6 6 14 7.1 14 77 14 `82 14 87 14 93 14 99 14104 `14110 :15 :6 .r6 12 15 v18 :15 :24 15 3 6 :15 35 15 .4 1 A1 5 :53 15 59 .15 :65 15 71 1 5 77 15 :82 `15 88 15 .93 15160 15103 15112 15 1 18 16 6 16 13 16 19 16 -25 16 V32 16 `38 16 44 16 457 16 :63 16 :69 16 76 16 82 16 :88 16 `94 16100 16107 16114 16120 16126- 17 7 `17 13 1720 17 27 17 r34 17 40 -17 47 -17 v60 h17 67 17 -74 -17 81 -17 88 `17 `94 -17101 17106 17114 17121 17128 17134 18 7 18 14 18 21 18 29 18 36 1843 18 50 18 64 18 72 18 78 18 86 18 93 18100 18107 18113 18121 18129 18136 18143 19 8 19 15 19 23 19 30 19 38 19 45 19 52 19 68 1 9 `76 19 83 1 9 91 19 98 19106 19114 19120 19129 19136 19144 19152 20 8 20 16 20 24 20 32 20 40 20 48 20 56 20 72 20 80 20 `88 --20 96 20104 20112 20120 20128 20136 20144 20152 20160 21 9 21 17 21 25 21 34 21 42 21 51 21.59 .21 ,76 .21 8.5 ,21 .93 21102 21110 21118 2 1127 21134 21144 21152 21160 21169 22 9 22 18 22 27 22 36 22 45 22 5 3 22 62 22 80 22 89 22 98 22107 22116 22125 22133 22140 22150 22166 22169 22178 23 9 2.3 19 23 28 23 37 23 47 23 A56 y:23 65 `23 84 23 95 23103 423112 23122 :23131 23140 23148 23159 23168 23177 23188 24 10 24 19 24 29 24 39 24 49 24 5 9 24 69 24 88 24 98 24108 24118 24128 24137 24147 24157 24167 24176 24186 24196 25 10 25 21 25 30 25 41 25 51 25 `61 25 .72 25 `92 25103 25113 25123 25134 25144 25154 25162 25174 25185 25195 25 206 26 11 26 21 26 32 26 43 26 54 26 64 126 75 26 I96 26107 261192612926140 26150 26161 26170 26182 193 26 204 26 215 27 11 27 22 27 34 27 45 27 56 27 67 27 78 27101 27 111 27123 27134 27146 27157 27168 27178 27191 27 202 27 213 27 224 28 12 28 24 28 35 28 47 28 59 28 70 28 82 28105 ;28117 28129 28140 28152 28164 28176 28185 28199 28210 28222 28 233 29 12 29 24 29 37 29 49 29 61 29 73 29 85 29110 29122 29,134 29146 29159 29171 29183 29|193 29207 29 220 9232 29244 30 13 36 25 30 38 30 51 30 63 30 76 30 89` 30114 30126 30140 30152 30165 30178 30190 30 202 30216 30.229 80242 30254 31 13 31 26 `31 40 31 53 31 `66 31 79 31 93" 31119 :31132 31145 31159 31172 31185 31198 31209 31225 314238 31252 31264 32 14 32 28 32 41 32 55 32 69 32 83 32 96 32124 ,32138 32151 32165 32179 32193 32206 32218 32 234 32248 32262 32 275 83 14 33 29 33 43 33 57:33 71 33 86 33100 3312933143 33157 33172 33186 33 200 33 214 33 226 33 243 33 257 33 272 33 286 34 15 34 30 34 45 34 59 34 74 84 89 34104 34130 34149 34163 34178 34193 34208 34228 34235 34252 34267 34282 34 297 35 15 35 31 35 46 35 62 35 77 35 92 35108 35139335154 35170 35185 35200 35 216 3 5 2.31 35 244 35 262 35 278 35293 35308 36 16 36 32 36 48 36 61 36 80 36 96 361.12 36 36144936160 36176 36192 36 208 36225 36 240 36253 36172 36 288 36304 36 320 37 17 37 33 37 50 66 83 37 99 371:16l 37133 37149137166 37183 37199 37215 37232 37249 37262 37282; 37299 37315 37 332 38 17 38 34 38 52( 38 69 38 86 38103 3812038146138155| 38172 38190 38206 38 224 38240 38258 38272 38292| 38310 38326 38344 39 18 39 36 39 54 39 71 39 89 39107 39125. 39143. 39:160 39178 39196 39214 39 232 39 249 39 268 39282 39 303; 39321 39338 39357 40 19 .4 0 37 40 .55 .40 .74 40 92 40111 40129l40148140166140185 40203 40222 40240 401258 40 277 40293 40 3145 40 332 40351 40 370 41 :19 41 38 41 57| 41 76 41 l96 `41115 41134 41153 41172` 41|191 41211 41229 41249 41:268 41287 41302 41325v 41344 2136i 41382 42 20 42 y 42 :60| 42 79 42 v99 :42119 42139 :42159 42,179 `42198 42l218 `42 238 `42 25S 42 278 42 298 42 814 42 337l 42 357 42 377 42 396 43 20 43 41! 43 62 43 82 44101 `43123 .43144 `43164 43185 431206 43226 43 247 43 267 431288 `43 309 43 326 43 349 43 369 43390 43 411 44.21 144 42, 44 `64| 44 85 44 106 :44128 44149I 44170 44191: 442212 44234 44255 44 276 447298 44320 44336 44361| 44 383 44404 44425 45 22 45 44' 45 66' 45 88 45110 45132I 45154| 45176L 45l198 45l220 45 45 2 45354 45376I .45 398 45 420 45 440 Cloths 0f 22 inches.

-Forl cloth. Ferl cloth. For 1` cloth. loiwl` cloth.

Dey. Ft..z'n. QDcg. '.Ft. in. Dey. .D eg. F6171. 46 1 11 5G 2 9 66 4 1 76 7 4 47 2 .0 57 2 101 `67 4 4 77 7 11 48 2 1 58 2 11 68 4 6 78 8 8 .49 2 2 59 3 1 69 4` 9. 79 9 -5 `50 2 3 60 3 2 70 5 0` 80 10 4 v51 2 3 61 3 4 71 5 4 `81 11 7 52 v2 4 A62 3 ,5 72 5 S 82 13 00 53 2 5 66 3 .7 73 6 0 83 14 11 54l 2 ,.6 .64 `3 9l 74- V6 5y 84 17 `5 55 2 7 65 3 11 75 6 1 0 8 5 20 11 g twenty-five degrees We 4 as the Whole 30 o in the column of degrees of No.

Cloths of 28 inches.

those denoting degrees. This latter is arranged in the tables to the nearest inch, vfractions of inches being omitted as of no vimportance in practice.

Columns No. l, No. 2, &c., to No. 2O rep- 20 resent the degrees and departure or depth of gore for any numbers of breadths of cloths of canvas in the sail, corresponding to the scertain the whole Oore in lifteen cloths the angle of gore bein look at 25 15 and opposite to it n the right hand adjacent column We have l5 i having tind the 0 .00999 999999002123456891 681 7 7 8507 2 nl2234 789012456789012346W891M3W5Mwm0m3578w19w I 1111.1111122222221233333334 44445555 0 123456789012345678901234567890123456789012345 N 111111111122222222223333333333444444. .990077655444322 2l24mo344507801 7336 6161639 N n 1234567890123Q567890123467%%0034mm8013467m I 11111111111222222222333333.6444Auh4555 0 123456789012345678901234567890123456781Wd012amm9 N 11111.1.111122222222223333333333444444 .9876432 098766544444444456780165703604 64004 .olo n 123456 8S9012345078901234568981245689M35780 I 1111111111222222222233333334444445 0 123456700901234567009012345670090123456789012@45 N 1111.]1111122222222223333333333444 4.4 .00753208764320900765 33222222345 891369 6 496 n 12345567890112345 78901234567902345WSMWMW4G7 I 1111111111122mV9Pnmm/22223333333I4444 0 12345678901234567890123456789012345678901245 N 111111111122222222223333333333444 4.4 .8 429743197542087643210099888990134680 0 38 n 233456778901223456789001234568901235M9M$34 I 11111111111222222222233wo43|3l31MV4|4l O 1234567890123456789012345678901234567S90123M5 N 11111111112222222222333339033334444 4 .7529 419.6429752086531087654433333 45790 5 6 .rm n 122 4556788901223456778901234567M90124^M-46w0w 6100397027 I 11111111111122222|W-|2-2i2i23B|3Mo|333344 .l 0 1234567890123456789012345678901234.5678901345 h N 111.L1111112222222222333333333344 4.44 am .74074185296.30852075319643108765554 55679146 1 M n 12234.4566789901223455678900123456Moo9012450wm^m-5 C I 11111111111122222222222321333333I 1 0 123456789012345678901234567890123456789012345 r N 111111111122222222223333333333444444 0 9.67890123M5 4 77778888 8 3 639528418417418418630752085320986655445608024 T n. 1 112334556778990112344,5(778901123456789012456 D I 111111111111122222222222333333 0 123456789012345678901234567890123456789012345 N 111111111122222222223333333333444444 u3691592728 i .62849517395184063963963074096020875433 222356 1 U n 1122344556778990012234556778901123456W890123 d .5556667788 I 11111111111111222222.,Q\2\2m3i|3.3i S 1m m O 123456789012345678901234567390123456789012345 6 C N 111111111122222222223333333333444444 .h l C 1 .516172839305172oo40628417307318530864219888788 n .1 1 n 11.223344566778890011233455677890012344567890 .Z 0 g6789012345 I 11111111111111122229122222223 F r66666777777 0 123456789012345670090123456789012345678901234.5 oo D N 111111111122222222223333333333444444 Z .50 0494940405050516283941739528529631975 1 w n 1M2223345566778899001123344566785011J3M7mw fw n579n124790 I 11111111h11l11112p2b||o522 i O 123456789012345678901234567890123456739012345 S um N 11111111112222222922233303333333444444 m 0 U3333444445 493826150 938382717272727394061840030742975 2 O d 9 W 1122334M45566778899001122344556775990112Sabre l 1 0. I 111111111111111Hv1h2i222.2.2i2l C I 123456789012345678901234567890123456789012345 1 N 111111111122222222223333333333444444 F0 .40o @m0409260 lomwwio..0l/.4.8.3T1605050494950617395185297. 8 n M1222334M.;45566o7788990011122344556678S9001m2A D 0. I 111111111111lllilddl2-2l22 1234567890123456789012345678901234567009012345 S 1 124 N 111111111122222222223333333333444444 L .M567 910 1 .370 71481582592604715937160493827272739506396 t 7 n 11H12223334445566677788990001122334455677889 0 tn/222223333 0. I 1111111111111111111 d F 1 34.567890123456700 0123456789012345678901 3 5 N 2 111111111 22222222223333333333444M4 1 .1 .36925001470369258158158158269371593002716161729 0 l 5 6 n 1112223333444555666777008899000112233445566 F I 111111111111111 0 12345670090123456700901234567890123456789012345 D N 111111111122222222223333333333444444 .2570257025702570350014792581581471482593726150 5 n. 11112222333344445555666777888999mwwHHHBwmM 0 123456789012345678901234567890123456789012345 N 111111111122222222223333333333444444 .24680 4680246000246913580257025703691471471482 4 Tn. 1m11122222333334444555566667777888999mwmu 0 1234567009012345678901234567890123456789012345 N 1111111111222222222233.33333333444444 4679023568913467912467913568025791368136814 3 m13 111111122222233333344444555556666777788 O 56789012345678901234567890123456789012345 N 1234 111111111122222222223333333333444444 .1 789012345678901345679124567891245780246 2 7n. 23456 111111111122222222333333334444445555 O 67890123456789012345678'20123456789012345 N 12345 111111111122222222223333333333444444 56677899001122344556778990123445678 J .m0112233445 111111111111111112222222222 0 1 56789012345678901234567890123456789012345 N 234 11111111lle/.2222222223333333333444444 principle ol 'sign O- for the Width of canvas cloths of 22 table of' cloths of 22 inches, if We Wish to 25 th to be measured up or down o-n the selvage for obtainin gore on `the foot, stay or leach as angle, Which the h each other, de-

sail-represented in number of the column. For instance in the These tables` are produced by trigonometvrical calculations on the the course and departure given to difference of latitude. The course may be 5 supposed to represent the tWosides of a sail make Wit noted in the tables by the degrees, the departure to be connected into a l0 the tables by the heading inches, cloths of 2S inches, &c. and the a difference of latitude the dep g' the 15 hereinbefore explained, and which 1s exhi ited in each of the columns adjacent to depth of gore. The process `of finding the depth is as follows:

log. cosine 25 log. 330

cr as expressed in igures =l\lo. of inches in 15 cloths log. sine 25o log. cosine 250 =9.95728 log. sine 25 =9.62595 log. 330 x2.51851 Therefore for 153.87 we insert 154 in the tables.

Having thus found the whole depth of gores one-fifteenth of 15e or 10i; inches (near enough for practice) will give the depth for one cloth which is nea-rer by one-quarter of an inch than is denoted in the double column No l, of the table against 25 degrees.

'I have here 0'iven but two tables as these are amply suilicient to exhibit the method on which others for cloths of less or greater width may be constructed.

Having thus explained the principles on which the tables are calculated, their application in practice will be easily understood by the following explanation of finding the gores of different sails. Suppose we desire the stay and foot gores of a jib we proceed as follows. Fig. 2, represents a jib the dimensions of which we will suppose to be equal to forty-tive feet on the stay B C; twenty-six feet on the foot or A B and thirty-three i'eet on the after leach or A C. If desired to find the stay and foot gores, represented by C a for the former and c d for the latter we arrange the scales as seen in Fig. 3; that is to say we take a distance 7L. f on D of live inches and two-tenths of an inch which, as the scale is live feet to an inch, is the required distance,.representing twenty-six feet. Next take on ruler A a distance g 7a equal to six inches and sixtenths ol an inch, this being the proportional distance or thirty-three feet, the length of the after leach, Lastly take nine inches from to g on ruler E, first placing the upright point y Fig. l, of the center of the rulers E F, through the small hole in the division of ruler D expressing five inches of two-tenths of an inch. Then bring the division expressing nine inches on the edge of ruler E to correspond with the division six inches and six-tenths of an inch on ruler A, and turning down the clamping nuts the space f g 7i., Fig. 3 will represent the required shape of the jib, the parallel lines on the card or paper under the ruler showing the number of cloths or stri s of canvass in the same. The index e' of tne ruler D will denote in the graduated semicircle e g Fig. 1, or e f g Fig. 3 the numbers of degrees in the angle of the foot gore, which we will suppose to be eight de grees (8O) that is the angle c e (Z Fig. 2, is equal to eight degrees. In the table headed cloths of 28 inc-hes we find against 8O in the double column No. 1, four inches (4c inches) as the depth of the foot gore for each cloth or c l Fig. 2:4 inches. But if we wish to obtain this measurement more exactly, we have only to count the number of cloths in the sail, which in Fig. 3 is found to be eleven. Then looking in double column No. 11, against 8 we have i3 inches for the whole gore; which divided by 11, (the number of cloths) gives a result ofV 3% inches, as the true depth of the foot gore of each cloth. In practice four inches are suliciently near.

The next operation is to ascertain the anglee of the stay gore or C a, Fig. 2. The graduated circle a; Fig. l, with the rule G should be brought into the position denoted in Fig. 3; that is to say, turn the circle round in its center until the side of the rule Gr is parallel to the perpendiculars denoting the sea-ms of the cloths; then the angle subtended between the inner edge of the rule E and the zero of the upper limb oir the circle .0c or center line of the rule G will be the complement of the angle required which in this case we lind is (3420) thirty-'four degrecs; subtracting this from (900) ninety degrees we have (560) fifty-six degrees for the angle :of the stay gore. Now on looking in the tables in the double column of degrees above (450) forty-five degrees, against (5Go), we iind 3 feet and 5 inches as the depth of C a Fig. 2, or the stay gore for each cloth.

As the foot of a jib for large vessels is seldom cut on a straight line but cuved as seen at A f B, Fig. 2, or in nautical language with a sweep,7 the mode I adopt for iinding the gores on the foot for each cloth is thus described. Bring the ruler I into the position denoted by the dotted lines in Fig.

3, or so that the curve of its upper edge shall pass through the point f. rIhen that portion of the curve of the ruler between zand f will exhibit the sweep of the foot.

The ruler I is not formed withV any particular curve but such a one may be adopted as will answer for dii'erent sails-or instead of one ruler we can employ twoA or three of dierent curves according to the pleasure-and taste of the sailmakers. The ruler I being in the position above mentioned, clamp it by the nut Ja- Next we remove the rulers E F G and circle m leaving the rulers D and I. First we wish to obtain the angle on which to cut the gore, A g 2, or the angle made bya chord A g with a line drawn through g parallel with D B. We .move the ruler D, downward until its upper edge coincides with the intersection of the line between the cloths 1, and 2, Fig. 3 and the upper curve of the rulei` T. This intersection coi'respoliclswvith the point g Fig. 2. Then the iducial edge of the index of the ruler D will denote the number of degrees in the angle required which in this case is (190). Then looking in the table we find in column No. 1, against (19o), in the adjacent column, the number' 10 or ten inches as the depth of the first gore. Then on cutting the first and t-he stay gores of the first and second cloths, in the manner before mentioned we measure off the length ZL g Fig. 2, of the after selvage of the second cloth by applying it to the free selvage of the first cloth. Our next operation is to obtain the angle of C/ ZL. Move the ruler D a short distance upward until its upper edge coincides with the point ZL or end of the divisional line between the second and third cloths. By inspecting the semicircle f g /t Fig. 2, we thus have the angle made by a straight line drawn from A to ZL Fig. 2, and a line through the point h. parallel D D, say equal to (18). Now looking in the table double column No. 2 against (18) we find 18 inches, as the depth of gore for two cloths. Then (18*10) eighteen minus ten leaves 8 inches as the depth of the gore ofthe second cloth.

For the foot of the third cloth we move the ruler D upward as before, and read off the angle between the points A z' and an imaginary line through vl Fig. 2, parallel to D B which in this case suppose to be (16o). Against (16o) in No. 3, denoting the third cloth, we find 24 inches as the whole depth of gore. Therefore subtracting from the same 1S or the sum of the dept-hs of the first and second cloths we have (6) as the depth of gore of the third cloth. Thenas in Fig. 4, as we are to form the foot of the third cloth, which we have already shaped on the angle of the foot g 72, of the second cloth, we must set off two inches from g to Z. Then Z m will be equal n c' or six inches. Gut from ZL` to Z and we obtain the true shape of the foot o f the third cloth. 1We continue, in a similar manner for the remaining cloths having previously made our calculations of the differences g Z for each cloth; if we are correct in setting off and cutting the slope A g of the first, we shall find no difiiculty in proceeding with the rest and thus we are enabled to cut a jib with or without a sweep on the foot.

I now proceed to exhibit the application of the scales tofinding the gores on the head, foot, and mast or fore leach of a trysail of the following dimensions.

Hoist on the trysail mast=94 feet. Length of trysail on the foot=57 feet. Do Do. head=27 feet.

Do of diagonal=39 ft. 6 inches. Do after leach=37 feet.

The rulers will be arranged asexhibited in Fig. 5; and in order to dispose them as therein represented, we first lay on ruler C the length from 7c to 7L corresponding to the diagonal which would be seven inches and nine-tenths of an inch. Through they division hole we insert the projecting pin y, Fig. 1, for the intersection of the rulers E and F, Fig. 5. Then lay off g 7L on ruler E equal to five inches, and four tent-hs of an inch, which gives us the length of the trysail on the head; also lay off g 7c equal to seven inches and four-tenths of an inch corresponding to the after leach. Clamp C and E in this position. Next set off Z on F equal to four inches and four tenths of an inch and z' 70 on D equal to seven inches and four-tenths of an inch. The space g L Z 7c cii'cumscribed by the rulers will thus exhibit the exterior of the trysail while the card or ruled paper on the board will show the number of cloths in the same.

The gore on the head is found by bringing the circle a and ruler G into the proper position denoted in Fig. 5, when we shall find that the ruler E will cut on the graduated circle the angle of the head gore which in this particular instance will equal {160)3 Then looking in the tables under double column No. 1 we find against (16) 8 inches as the depth of gore required.

rEhe gore on the foot is determined by the angle which the index of the ruler D indicates o-n the graduated semicircle. e 7 g which in this particular case is twelve degrees (120) against (12o) in the tables we find 6 inches as the depth of the foot for each cloth The gore on the mast or fore leach is determined by the angle which the inner edge of the ruler F cuts on the graduated circle which is the complement of the angle of gore. In this case the gore angle will equal and the depth of the gore will equal 5 feet.

The next sail in order is the square mainsail Fig. 6, and we now proceed to determine the gore on the side leaches and roach of the foot by the application of the scales and tables. As on inspection of Fig. 6 it will be perceived that both sides of this sail are alike, or A E F C equals D B E F We have only to project one-half by the scales. In this case it Will readily be seen from the foregoing explanation, that by laying off a can obtain the angles for the side gores; and

also by reversing the ruler I so as to form the roach of the foot or F D, We can obtain the angles of the gores of the feet of strips or cloths, in a similar manner and by similar principles to those heretofore described in the explanation of the mode of finding the sweep of a jib. As all this Will be easily understood by any sail maker, from the principles heretofore explained, it is unnecessary to go into any more particular description of the same. As a straight ruler H divided as seen inFig. l, and having screws and nuts a3 b3 is sometimes convenient, during the operations of determining the angles and dimensions of other sails, and may be used according to the pleasure of the sail maker, I have added one to my collection of scales, but I do not consider it as embraced in my ina-in collection, buit merely secondary to the same.

p Having herein-above explained the construction of my mathematical scales, and tables together With their practical application, I now proceed to specifically point out,

such parts thereof I claim to be my invention- 1. I claim, the scales A and B, in combination With the scales C D E F, ruler G, and circle ai, the Whole constructed, arranged, graduated and operating together, substantially in the manner above mentioned and described, fo-r the p-urpose of determining the angle of the gores on t-he head, foot and leaches of different sails as herein above explained.

2. I also claim, the combination, With the above specified parts of the ruled table or card e f g b, constructed and arranged substantially as above described for the purpose of determining the number of breadths or cloths of canvass in a sail, in the manner herein-before explained.

3. Furthermore, I claim, the curved ruler I, constructed and arranged substantially as above described, in combination With the ruled table or card e f g h and the scales A and D, for the purpose of determining the angles of the gores of the roach or sweep of the foot of a sail, in the manner herein before explained.

In testimony that the above is a true description of my said invention and improvement I have heretofore set my signature this fifth day of December in year eighteen hundred and forty.

JOHN DOMINIS. 'Witnesses 4 IVM. JARRETT, IVILLIAM LADD. 

